This proposal is to further develop and clinically test a new method of tum r radioimmunodetection developed by the applicant's research group. This approach is a merging of tumor immunology and nuclear medicine techniques, and consists of performing total-body photoscans and tomograms in patients receiving an antitumor antibody labeled with a gamma-emitting radionuclide. The anti-tumor antibody is a goat immunoglobulin G prepared against carcinoembryonic antigen and purified by sequential affinity chromatography cycles. This study will further evaluate the use of this method in tumor detection and localization in proven cancer patients, it will assess the possible role of this technique in initial tumor diagnosis, and it will determine the overall use of this new cancer detection method in the management and clinical staging of cancer patients. Evaluation of other radiolabeled anti-CEA IgG and Fab preparations will also be pursued. Finally, a major effort will be made to develop and refine computer-assisted subtraction techniques in regular scintillation scans and in tomograms for appropriate compensation of blood pool background radioactivity. Radionuclides used in subtraction will include 99m-Tc and 123-I, while the principal radionuclide to be used in labeling our specific anti-CEA antibody will be 131-I.